A method for preparing hmf by catalyzing fructose and sucrose conversion with a eutectic solvent system

Abstract

The application discloses a method for preparing HMF by catalyzing fructose and sucrose conversion by using a eutectic solvent system, which uses the eutectic solvent as a catalyst and a solvent at the same time, and fructose or sucrose as raw materials, and converts the fructose or sucrose into HMF at 60-80 DEG C for 0.5-1 h, wherein the eutectic solvent is obtained by mixing a hydrogen bond acceptor and a hydrogen bond donor and stirring at 50-70 DEG C for 5-10 min. The method uses the DES with a proper proportion and composition selected to be both a solvent and a catalyst, and converts the fructose and sucrose into 5-hydroxymethylfurfural, and the conversion rate of the 5-hydroxymethylfurfural can reach more than 79%, compared with a conventional 5-hydroxymethylfurfural preparation route, the method has the advantages of simplicity, mildness and high efficiency, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of HMF preparation technology, specifically to a method for preparing HMF by catalyzing the efficient conversion of fructose and sucrose using a eutectic solvent system. Background Technology

[0002] 5-Hydroxymethylfurfural (HMF) is a bio-based precursor for many industrially valuable chemicals. Currently, in industrial HMF production processes, a relatively high yield of HMF can be achieved through Brønsted acid (…). Fructose dehydration is achieved by catalyzing the reaction of ionic acid in water, organic solvents, or ionic liquids. According to literature, ionic liquids can be used as solvents to gently and efficiently convert sugars into HMF. However, although ionic liquid systems possess various properties beneficial to chemical synthesis processes, such as high thermal stability, wide solubility in solution, and low melting point, their high cost has always limited their industrial application.

[0003] Eutectic solvent (DES), as a simple and cost-effective green solvent, has also attracted researchers' attention in HMF preparation reactions. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, the present invention aims to provide a method for preparing HMF by catalyzing the conversion of fructose and sucrose using a eutectic solvent system.

[0005] The technical solution of the present invention is as follows: a method for preparing HMF by catalyzing the conversion of fructose and sucrose using a eutectic solvent system, wherein the eutectic solvent is used as both catalyst and solvent, fructose or sucrose is used as raw material, and the conversion reaction is carried out at 60-80℃ for 0.5-1h, thereby converting fructose or sucrose into HMF.

[0006] Furthermore, the eutectic solvent is obtained by mixing a hydrogen bond acceptor and a hydrogen bond donor and stirring at 50-70°C for 5-10 minutes, preferably at 50°C for 10 minutes.

[0007] Furthermore, the present invention further specifies that the hydrogen bond acceptor is choline chloride, and the hydrogen bond donor is one or more of aluminum chloride hexahydrate, maleic acid, oxalic acid, p-toluenesulfonic acid, glutaric acid, boric acid, citric acid, malic acid, malonic acid, glycolic acid, and ethylene glycol, preferably maleic acid or a mixture of maleic acid and ethylene glycol.

[0008] Furthermore, the present invention also specifies that the molar ratio of hydrogen bond acceptor to hydrogen bond donor is 2-4:1-3.

[0009] Furthermore, the present invention specifies the following preparation process: Hydrogen bond acceptors and hydrogen bond donors are added to a glass reaction flask according to the feeding ratio, and reacted at 50-70°C for 5-10 minutes to form a transparent solution, which is the eutectic solvent; fructose or sucrose is added to the eutectic solvent, and the reaction is carried out at 60-80°C for 0.5-1 hours. After the reaction, a small amount is taken out and diluted in a volumetric flask. The components in the reaction solution are analyzed, and the results show that the main component in the reaction solution is 5-hydroxymethylfurfural. The reaction is then terminated, yielding a solution containing 5-hydroxymethylfurfural.

[0010] Furthermore, the present invention also specifies that the conversion reaction temperature is 70°C and the reaction time is 0.5 h.

[0011] In industrial production, over 80% of chemical substances constitute solvents. From a commercial perspective, an excellent solvent not only needs to achieve good yields but also good profitability. The purpose of this invention is to provide a greener, cheaper, and more efficient eutectic solvent (DES) system for the gentle and efficient conversion of fructose and sucrose into 5-hydroxymethylfurfural (HMF). The DES of this invention can be formed by a simple mixture of hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA). This not only significantly reduces reaction temperature, energy consumption, and byproduct formation, but also, due to hydrogen bonding, allows for better dissolution of raw materials. Furthermore, fructose can participate in the formation of DES in the choline-based DES system, further improving HMF yield. Since the hydrogen bond donors used in this invention can contain acidic groups such as carboxylic acids (e.g., maleic acid, oxalic acid, p-toluenesulfonic acid, malonic acid, etc.), the DES using these organic acids as melt components is strongly acidic, giving it the potential to act as a catalyst for HMF conversion.

[0012] This invention utilizes DES of appropriate proportions and composition, which can act as both a solvent and a catalyst, to efficiently convert fructose and sucrose into 5-hydroxymethylfurfural. The conversion rate of 5-hydroxymethylfurfural can reach over 79%. Compared with conventional 5-hydroxymethylfurfural preparation routes, it has the advantages of being simple, mild, and efficient, and has good prospects for industrial application. Detailed Implementation

[0013] The technical solution of the present invention will be further described in detail below. Those skilled in the art should understand that the specific embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof.

[0014] It should be noted that, unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art, and the raw materials used are all commercially available conventional products.

[0015] The following examples will provide a detailed explanation.

[0016] First, eutectic solvents with different components are prepared. The specific preparation method is as follows:

[0017] Maleic acid, ethylene glycol, and choline chloride were added to a glass reaction flask in a molar ratio of 1:1:1 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-1.

[0018] Maleic acid, ethylene glycol, and choline chloride were added to a glass reaction flask in a molar ratio of 1:1:2 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-2.

[0019] Maleic acid, ethylene glycol, and choline chloride were added to a glass reaction flask in a molar ratio of 1:1:3 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-3.

[0020] Maleic acid, ethylene glycol, and choline chloride were added to a glass reaction flask in a molar ratio of 1:1:4 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-4.

[0021] Maleic acid and choline chloride were added to a glass reaction flask in a molar ratio of 1:3 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-5.

[0022] Ethylene glycol and choline chloride were added to a glass reaction flask in a 1:1 molar ratio and stirred at 50°C for 10 min to form a transparent solution, which was DES-6.

[0023] Maleic acid and ethylene glycol were added to a glass reaction flask in a molar ratio of 1:4 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-7.

[0024] p-Toluenesulfonic acid, ethylene glycol, and choline chloride were added to a glass reaction flask in a molar ratio of 1:1:3 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-8.

[0025] Malic acid, ethylene glycol, and choline chloride were added to a glass reaction flask in a molar ratio of 1:1:3 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-9.

[0026] Aluminum chloride hexahydrate, ethylene glycol, and choline chloride were added to a glass reaction flask in a molar ratio of 1:1:3 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-10.

[0027] Citric acid, ethylene glycol, and choline chloride were added to a glass reaction flask in a molar ratio of 1:1:3 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-11.

[0028] Glutaric acid, ethylene glycol, and choline chloride were added to a glass reaction flask in a molar ratio of 1:1:3 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-12.

[0029] Malonic acid, ethylene glycol, and choline chloride were added to a glass reaction flask in a molar ratio of 1:1:3 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-13.

[0030] Glycolic acid, ethylene glycol, and choline chloride were added to a glass reaction flask in a molar ratio of 1:1:3 and stirred at 50°C for 10 minutes to form a transparent solution, which is DES-14.

[0031] Examples 1-7

[0032] Example 1: 20g of the DES-1 prepared above was taken as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0033] In Example 2, 20g of the DES-2 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0034] In Example 3, 20g of the DES-3 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0035] In Example 4, 20g of the DES-4 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0036] In Example 5, two 10g portions of the DES-5 prepared above were taken as the reaction solvent and catalyst, and 4g of fructose were added to them respectively, and the reaction was carried out at 70°C for 30 minutes and 1 hour.

[0037] In Example 6, 20g of the DES-6 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0038] In Example 7, 20g of the DES-7 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0039] The reactants were then filtered and analyzed using an Agilent 1260 high-performance liquid chromatograph with a PLHi-Plex H column (300×7.7 mm, 8 μm) at a flow rate of 0.6 mL / min. 5 mL of H2SO4 solution was used as the mobile phase, the detector temperature was 60 °C, external standard method was used for quantification, and the yield of HMF was calculated.

[0040]

[0041] The results showed that the main component in the reaction solution was 5-hydroxymethylfurfural, as well as a small amount of unreacted fructose and levulinic acid. The HMF yield results are shown in Table 1.

[0042] Table 1: Fructose Conversion by DES1-7

[0043]

[0044]

[0045] As can be seen from the data in Table 1, the use of DES as a catalyst and solvent in this invention has a relatively good effect on fructose conversion. This is because fructose can further participate in the formation of DES during the reaction, and under the action of hydrogen bonding, it is beneficial to the conversion of fructose to HMF. Choline chloride and maleic acid play a significant role in DES; for example, in Example 7, where there is no hydrogen bond acceptor choline chloride, the reaction basically does not occur. Although ethylene glycol can adjust the viscosity of DES, in Example 6, where the only hydrogen bond donor is ethylene glycol, the reaction also basically does not occur. Furthermore, under acidic conditions with maleic acid, the yield of HMF can be adjusted by changing the proportion of choline chloride; for example, the maximum yield of HMF was obtained in Example 3.

[0046] Examples 8-14

[0047] In Example 8, 20g of the DES-8 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0048] In Example 9, 20g of the DES-9 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0049] In Example 10, 20g of the DES10 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0050] In Example 11, 20g of the DES-11 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0051] In Example 12, 20g of the DES-11 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0052] In Example 13, 20g of the DES-11 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0053] In Example 14, 20g of the DES-11 prepared above was taken out as a reaction solvent and catalyst, and 4g of fructose was added to it and converted at 70°C for 30 minutes.

[0054] The reactants were then filtered and analyzed using an Agilent 1260 high-performance liquid chromatograph with a PLHi-Plex H column (300×7.7 mm, 8 μm) at a flow rate of 0.6 mL / min. 5 mL of H2SO4 solution was used as the mobile phase, the detector temperature was 60 °C, external standard method was used for quantification, and the yield of HMF was calculated.

[0055]

[0056] The results showed that the main component in the reaction solution was 5-hydroxymethylfurfural, along with small amounts of unreacted fructose and levulinic acid. The HMF yield results are as follows:

[0057] Table 2: Fructose conversion of DES8-14

[0058]

[0059]

[0060] As can be seen from the data in Table 2, the use of DES with different acidity affects the yield of HMF, and maleic acid has the best effect under the same molar ratio conditions.

[0061] Examples 15-16

[0062] In Example 15, two 10g portions of the DES-1 prepared above were taken as the reaction solvent and catalyst, and 4g of sucrose was added to each portion, and the mixture was converted at 70°C for 30 minutes and 60 minutes, respectively.

[0063] In Example 16, two 10g portions of the DES-5 prepared above were taken as the reaction solvent and catalyst, and 4g of sucrose was added to each portion, and the mixture was converted at 70°C for 30 minutes and 60 minutes, respectively.

[0064] The reactants were then filtered and analyzed using an Agilent 1260 high-performance liquid chromatograph with a PLHi-Plex H column (300×7.7 mm, 8 μm) at a flow rate of 0.6 mL / min. 5 mL of H2SO4 solution was used as the mobile phase, the detector temperature was 60 °C, external standard method was used for quantification, and the yield of HMF was calculated.

[0065]

[0066] The results showed that the main component of the reaction solution was 5-hydroxymethylfurfural, as well as a small amount of unreacted sucrose, fructose, and levulinic acid. The results are shown in Table 3.

[0067] Table 3: Conversion of sucrose by maleic acid DES

[0068]

[0069] As can be seen from the data in Table 3, 60 min significantly improves the HMF yield of sucrose compared to 30 min. When choline chloride and maleic acid are mixed in a 3:1 molar ratio to obtain a eutectic solvent for the reaction, the HMF yield is as high as 79.73%, which is higher than the HMF yield of the same mass of fructose. This may be due to the unique reaction mechanism of sucrose in this choline-DES system. Under the action of hydrogen bonding, sucrose may degrade into glucose and a very active fructose-furanosyl cation. This cation can be effectively and directly converted into HMF, making it easier to generate HMF precursors and further improving the HMF yield.

Claims

1. A method for preparing HMF by catalytic conversion of sucrose using a eutectic solvent system, characterized in that... Using a eutectic solvent as both catalyst and solvent, and sucrose as raw material, sucrose and the eutectic solvent at a mass ratio of 4:10 are converted at 70°C for 60 min to obtain the eutectic solvent. The preparation process of the eutectic solvent for converting sucrose into HMF is as follows: maleic acid and choline chloride are added to a glass reaction flask at a molar ratio of 1:3, and stirred at 50°C for 10 min to form a transparent solution.

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